I can't mutate or query in SvelteKit

// api.ts file in lib folder
import { createTRPCProxyClient, httpBatchLink } from '@trpc/client';
import type { AppRouter } from '../../../backend/src/router';

export const api = createTRPCProxyClient<AppRouter>({
    links: [
        httpBatchLink({
            url: 'http://localhost:5173/api',
            // You can pass any HTTP headers you wish here
            async headers() {
                return {
                    authorization: (localStorage.getItem('token')
                        ? localStorage.getItem('token')
                        : '') as string
                };
            }
        })
    ]
});